With the increased use of electronic medical devices in surgical operations, the energy that is required to perform a surgical procedure has become a significantly more meaningful consideration. Furthermore, and perhaps most importantly, the clinical consequences of using excessive energy may have a significant effect on the surgical result. This is particularly so in the case of ophthalmic surgery where visual rehabilitation is of the utmost importance.
Within the general field of ophthalmic surgery, the concern here is specifically on cataract surgery. Conventional cataract surgery involves emulsification of the crystalline lens with an ultrasonic handpiece (a process known as “phacoemulsification”) and aspiration of the emulsified lens from the eye. In this process the lens tissue that is to be removed is broken up into relatively small fragments (i.e. emulsified). The emulsified fragments are then aspirated from the lens capsule by, e.g., an aspiration needle. As a practical consideration, phacoemulsification can be a relatively time consuming task that requires the use of a substantial amount of ultrasonic energy.
In comparison with a typical application of ultrasonic energy, it is known that substantially less energy is required to perform Laser Induced Optical Breakdown (LIOB) on optical tissue. Moreover, LIOB can be accomplished with much greater precision. A consequence of this is that femtosecond lasers are now widely accepted for use in ophthalmic surgical procedures, increasingly including cataract surgery.
In a recent article entitled “Effect of Femtosecond Laser Fragmentation of the Nucleus with Different Softening Grid Sizes on Effective Phaco Time in Cataract Surgery,” J Cataract Refract Surg., 2012, Ina Conrad-Hengerer, MD, et al. reported on energy considerations in cataract surgery. In this article they concluded that, in a pretreatment for cataract surgery (i.e. lens fragmentation), a femtosecond laser-assisted system which used a relatively smaller fragmentation grid (i.e. laser guidance pattern) resulted in a significantly lower phacoemulsification time (i.e. less energy requirements).
Given that fragmentation grid size is an important consideration in a pretreatment for cataract surgery, there are still additional considerations which can be addressed. In particular, the effect that fragment configuration may have on the efficacy of a lensectomy is still an open question. Further, the question as to how the resultant fragments may interact with, and possibly hinder, each other during the lensectomy is worth consideration.
In light of the above, it is an object of the present invention to provide a system and method for performing a femtosecond lens fragmentation (pretreatment) procedure, on tissue in the crystalline lens of an eye, which configures lens fragments to facilitate their removal from the lens during a lensectomy. Another object of the present invention is to provide a system and method for performing a femtosecond lens fragmentation (pretreatment) procedure which configures lens fragments in a manner that will minimize interactions between adjacent fragments that would otherwise hinder their removal from the lens during a lensectomy. Still another object of the present invention is to provide a system and method for performing a femtosecond lens fragmentation (pretreatment) procedure which is simple to implement and is relatively cost effective.